Adjustable sound optics for cineprojectors



Dec. 5, 1944.

ADJUSTABLE SOUND OPTICS FOR CINE-PROJECTORS Filed April 26, 1943' A. F. VICTOR 2,364,495

Patented vDec. 5, 1944 ADJUSTABLE SOUND OPTICS FOR CINEPROJECTORS Alexander Ferdinand Victor, New York, N. Y.

Application April 26, 1943, Serial No. 484,659

Claims.

This invention relates broadly to sound translation or sound reproduction, and specifically the improvements have reference to a structure generally known as sound optic that is adapted for use in connection with motion pictures produced with synchronized sound. The present device is particularly applicable to cinematographic projectors employing the sound-on-film principle wherein a margin of the film strip is provided with a longitudinal track upon which the sounds are photographically imposed. In use, this film with its sound track is moved past a slit element that is interposed between a photo-electric cell and an exciter lamp, with the result that light waves passing through the slit are influenced optically by means of suitable lenses. The present invention is especially directed to the-slit element and the lenses which are coordinated therewith as well as to the manner of mounting the device and the complete envelopment of the part in a drum or housing. 1

It is an object of the present invention to provide a structure of the character described that is novel in the arrangement of its component parts, and which is effective and dependable in the performance of its functions. Other objects are to provide a sound optic device that is made i of simple and sturdy parts that will not readily get out of order, and which is economical to manufacture so that it may be cheaply produced and sold for a reasonable retail price.

Other objects and advantages of the present invention will be apparent to persons skilled in the art after the nature of the device is understood from the following disclosure. This invention embodies substantially the novel construction, combination, and arrangement of parts that are hereinafter fully described and illustrated in the accompanying drawing, and a finally pointed out in the appended claims. The invention is herein shown in a practical or typical embodiment.

In the drawing:

Figure 1 is a vertical side elevation of a unitary sleeve or drum in which the sound optic and lamp are housed, which element is removably mounted upon a wall or other support on a motion picture projector.

Figure 2 is vertical axial section of the sleeve or drum shown in Figure 1, the structure beingremoved from the support.

Figure 3 is a view looking into the right-hand end of Figure 2.

Figure 4 is a vertical section of the s1it-forming elements and the optical unit removed from the sleeve or drum and greatly enlarged for clearness.

Figure 5 is a vertical section taken on the plane of line 5-5 on Figure 4.

Figure 6 is a perspective of a fslit forming member removed from the optical housing and shown on an exaggerated scale.

The drawing is more or less schematic, and in the different views the same reference characters are used to identify like parts wherever they appear.

One of the sides of a wall or standard II] which supports the body and mechanism of the cinematographic projector is provided with a cylindrical boss ll disposed with its axis in a horizontal plane adjacent a housing l2 for a photoelectric cell it. The cell housing i provided with an aperture l2a. In the rear of this boss there is provision for a socket to receive and support the exciter-lamp I4, and surrounding this exciter lamp there is a cylindrica1 drum or shell l5 that is removably secured in the boss I I by means of a thumb-screw that screws through a tapped lateral hole in the boss and has its inner end bearing against the outer surface of the wall of the-drum or shell l5. The outer portion of the drum or shell is closed by a cover l'l'and a semicylindrical film guide and channel member I 8 is secured by screws l9 upon the outer face of the segment of the drum or shell which i nearest the photo-electric cell I 3. The guide member has spaced parallel guide shoulders 2! near its edges which are adapted to support the margins of the film during its travel in an arcuate path between the exciter lamp M housed in drum [5 and the photo-electric cell I3. There is a slot 22 in the segment of the inner guide-shoulder nearest the cell I3, which slot extends transversely through the guide member and is of a length to extend entirely across the sound optic unit that is positioned below said slot. The sound-track on the adjacent margin of the film registers with this slot 22 when the film is moving on the guide memher or track.

The drum or shell is of cylindrical shape and hollow and is adapted to completely surround and house the exciter-lamp and the sound-optic with its slit-forming elements.

Below the slot 22 the drum has a radially bored opening 23 that preferably alines with the axis of the sound optic unit, which unit is mounted within the drum in a manner which permits said unit to be bodily adjusted with relation to the film in directions toward and from the latter as will later be described herein.

The novel sound optic unit herein disclosed embodies elements for forming a slit and also oertain optical elements in co-ordinated relation thereto. After these parts have been adjusted to proper relation to each other the whole structure, as a unitary member, is adapted to be anchored to the mounting structure which is adjustably secured to the drum. The unit preferably comprises a body member 24 that is of cylindrical shape and has its exposed outer end 25 of the convex contour. A sleeve member 26 surrounds.the major portion of the body member and has an annular flange 21 near its lower portion that is utilized in securing the unit to its adjustable mounting structure. A set-screw 46 anchors the body 24 in the sleeve 26. The end of the sleeve that is remote to the convex end of the body member has a transverse wall 28 or inwardly-extending annular flange, that provides a central aperture 29 for the passage of light waves. A shoulder 30 is formed on the inner portion of the transverse wall 28 by increasing the diameter of the aperture 29, which shoulder constitutes a seat inside the end of the sleeve for the double convex condensing lens 3 I.

The body member 24 is hollowed-out by providing an axial bore 32 that extends up into the body from its lower or inner end, and there is a small rim or bead 33 on the inner or lower end face of the body surrounding the entrance to the bore 32. When the sleeve and body are properly assembled, the rim or bead 33 will bear against the adjacent annular margin of the condensing or converging lens 3i and maintain it in position upon its seat 30. The body member is provided with a transverse bore 34 in its upper portion close to the convex outer end 25, which bore is transverse to the axisof the body member. This transaxial bore 34 is of such diameter that its upper and lower segments cut through the body at the inner end of the bore 32 and at the convex outer end 25 of the body member. This provides upper and lower elongate openings or slots 35 and 36 respectively for passage of light waves. As will be seen the bore 34 extends entirely across the upper or outer portion of the body 24 so that an elongated cylinder lens 3'! may be inserted into the body through the side of the latter- The use herein of the term cylinder lens is intended to define a lens of substantially circular crosssection, or a lens having a curved surface or surfaces all portions of which are concentric to or equi-d-istant from the longitudinal axis of the lens. I r

Near the lower or inner end of? the body 24 there is another trans-axial bor 38 that opens into the central bore 32'. This bore 38 receives the slit-forming elements which are 'of special and novel construction. As shown in Figure the end portion 39 of the slit element is cylindrical and has a transverse groove 40 for a screwdriver or other tool and its. remaining portion 4| is semi-cylindrical so that when the slit elements are inserted through opposite ends of the bore 38 the faces of the semi-cylindrical portion of the two elements will oppose each other and the cylindrical portions 39 of the elements Will'be rotatably mounted in the trans-axial bore 38. The semi-cylindrical portions are not precise halves of the cylindrical part 39, but they preferably are slightly less than a halfv cylinder. The face of. the slit element is formed slightly con-- cave as shown at 4,2 in Figure 5, sothatwhen the slit elements are mounted in opposition to'eacliother in bore 38, either or both ends of these:

' core or shell and is locked in place.

elements may be rotated to increase or diminish the minute gap between the edges of the semicylindrical portions. The optical light slit formed by this gap is capable of adjustment as to size and also as to its position relative to the optical axis of the sound optic unit.

It will be noted that the axes of the lenses 31 and 3 I, and the "slit forming element all coincide and are in'alignrnent with each other. The sleeve member 26 is long enough to be disposed across the ends of the slit forming elements so that after proper adjustment has been made and the body 24 inserted into the sleeve 26 all of these parts, as well as the condensing lens 3|, are definitely maintained in position and cannot be tampered with because of the fact that the unit is thereafter inserted into its bored seat in the The aerial image of the slit is focused by the condensing lens in the small space between the slit and the inner surface of the cylinder lens and close to the latter, and said cylinder lens intensifies the image of the slit to pass it through the sound track on the film to the photo-electric cell.

As hereinbefore stated the sound-optic unit is adapted for adjustment toward and from the slot 22 in the film guide. In order to accomplish this the lower end 43 of the optic unit below the flange 2'! is inserted into a circular opening 44 made in the central portion of an elongated plate 45 of rectangular shape that extends longitudinally of the drum as shown. The sleeve, if desired, may be anchored to plate 45, although it may be found convenient to allow it to seat in the aperture and secure it b means of the flexible member that is shown herein. Near the ends of the plate 44 there are internally threaded stubs 47 that project from the plate in the same direction as the sound-optic unit, and screws 48 enter these stubs and have their heads countersunk in apertures in the adjacent portion of the cylindrical drum or shell l5. By turning the screws 48 in one direction'or the other, the plate 44 and the sound-optic unit are moved toward and from the film sound track in the film guide In order to stabilize the mounting structure and 'to maintain the unit on the .plate 45, a slightly flexible metal strip 49 is disposed upon the surface of the plate 44 which is nearest the film. This strip 49 is of rectangular outline and is approximately the same length as plate 44 but it is of greater width than said plate so that its longitudinal margins 50, which are obliquely bent, will contact the inner surface of the cylindrical drum or shell I5. At its central portion the metal strip 49- has opening 5| that closely surrounds the sleeve 23 of the sound-optic, and adjacent its ends the strip '49 is provided with recesses that open through its transverse margins and are of suflicient dimensions to accommodate the stubs 73- inuse in order to maintain the sound track of the film in proper focus with the lens system in the sound-optic.

What is claimed is:

1. A device of the kind described embodying a hollow cylindrical drum; a slotted film-guide upon the exterior of said drum; a lamp within said drum; a sound-optic unit disposed between said lamp and the slotted portion of said filmguide; a floating supporting-plate upon which said unit is secured; said plate extending Within said drum in the general direction of the axis of the latter; a flexible strip engaged intermediate its longitudinal margins with said supportingplate, the margins of said flexible strip disposed in contacting relation with said drum; and adjusting means carried by adjacent portions of said drum, said means coacting with said plate and adapted to move said plate against the tension of said flexible strip.

2. An arrangement of the kind described comprising a film guide having an aperture; an exciter lamp alined with said aperture; and a sound optic assembly interposed between said exciter lamp and said aperture; said assembly comprising a holder mounted on said guide; a hollow body member adjustably mounted in said holder; a seat in said holder back of said body in confronting relation thereto; a condensing lens in said assembly adjacent said exciter lamp and maintained in position by the inner portion of said body; a cylindrical lens in the outer portion of said body in spaced relation to said condensing lens and in axial alinement therewith; and litforming means in said assembly intermediate said lenses; the arrangement adapted to effect passage of light rays from said exciter lamp in succession through said condensing lens, said slit, and said cylindrical lens.

3. An arrangement as defined in claim 2 wherein, the condensing lens is disposed in said seat and the slit-forming means is mounted in said body.

4. A unitary assembly for the purpose described comprising a hollow holder; a cylindrical body mounted in said holder and having an axial bore opening through an end thereof, said body provided with parallel transverse bores intersecting its axial bore and spaced from the open end thereof; a condensing lens at the open end of said axial bore; a cylindrical lens in the transverse bore that is farthest from said condensing lens and sheathed by the adjacent portion of said body; and slit-forming means in the transverse bore that is nearest said condensing lens.

5. A unitary assembly as defined in claim 4,

wherein the transverse bores open through the sides of said body, and the holder masks the ends of the transverse bore containing the slit-forming means thereby to prevent access to said means and movement thereof.

ALEXANDER FERDINAND VICTOR. 

